SOme people like the eye candy and dont feel 30 FPS is playable in FPS. I like eye candy and 30 FPS in an FPS is unplayable for me. Its all subjective. But a 550 ti isnt a very powerful card for 1080p gaming period.
You will get 30-35fps at High settings without AA.. I have used that card.. I played with ultra @ 720p but after upgrading my monitor to 1080p I had to play with high.. Also you wont get more than 40fps..